Morphology Evolution and Improved Electrochemical Properties of LiFePO4 Cathode Materials for Li-ion Batteries

Abstract

LiFePO4 powders with different sizes and shapes were successfully synthesized in water, ethylene glycol, and mixed water/ethylene glycol solvents. The morphological evolution of LiFePO4 crystals from micrometer-sized bulky particles to nanorods was easily achieved by varying the water-to-ethylene glycol volume ratio. The morphological evolution process and formation mechanism were investigated. Electrochemical measurements showed that the charge transport and the diffusion rate of Li ions significantly improved with the structural evolution. The initial discharge capacity at 0.1 C was increased from 61 mAh∙g-1 for micrometer-sized bulky particles to 164 mAh∙g-1 for nanorods. Furthermore, the LiFePO4 nanorods exhibited a discharge capacity of about 120 mAh∙g-1 at 20°C and an excellent rate capability at high discharge rates.